A number of substituted dihydrocinnamaldehydes are known odoriferous substances. W. Berends and L. M. v.d. Linde, Perfumery and Essential Oil Record, 58, 372 (1967). Some of these compounds, particularly p-isopropyl-.alpha.-methyldihydrocinnamaldehyde and p-t-butyl-.alpha.-methyldihydrocinnamaldehyde, are among the principal aromatic compounds used in the industry.
These compounds are usually made by the multistep process shown below which involves a condensation reaction of an aromatic aldehyde with the .alpha.-methylene of an aliphatic aldehyde ##STR1##
Other methods of synthesis are reviewed in the Berends article above. (R and R' are suitable substituents provided to illustrate the general utility of the prior art processes).
The success of this multistep process necessarily depends on the availability of the appropriate corresponding benzaldehyde and the ability to minimize side reactions such as self condensation of the aliphatic aldehyde and/or the Cannizzaro reaction.
More recently, U.S. Pat. No. 4,182,730 described a method for converting an aryl alkyl ketone to the desired .alpha.-alkyldihydrocinnamaldehydes in a process which involves the Vilsmeier reaction as illustrated below. ##STR2##
Nothing in the prior art discloses or suggests the novel process and intermediates disclosed herein.